I will go a few minutes to help you out, the big Q however is have you got half hour to spare how to get valid value for your bucks ?
To be up front I have not looked at any of your links " because " in your price range all that matters is CONDITION that will outlast your investment, not make - model or miles.
Study this link
http://www.usedcartips.org/TESTDRI.html and go test drive any one of your picks, should vehicle pass your expectations then step 2 and 3 will be independent mechanical inspection along with a history report and if still a go, the final step will be negotiations.
Here is another link that may be of interest
http://www.usedcartips.org/TENTHOU.html
I know it's putting a lot on your plate all at once and can be confusing, feel free to ask further questions